Circuit breaker



March 29, 1949. w'. L. BUTLER 2,465,789

' CIRCUIT BREAKER Original Filed Nov, 15, 1946 2 Sheets-Sheet 1 T. H IDW1 mmmfi o w m w l. 1 L m 14. l m HME m m mm w k I a? Mrch 1949- w.BUTLER 2,465,789

CIRCUIT BREAKER Original Filed Nov. 15, 1946 2 Sheets-Sheet 2 Inventor:WIHIam LawrenceBufiler,

by ZZNL His Attorney Patented Mar. 29, 1949 CIRCUIT BREAKER WilliamLawrence Butler, Schenectady, N. Y., assignor to General ElectricCompany, a corporation of New York Original application November 15,1946, Serial Divided and this application tober 17, 1947, Serial No.780,403

4 Claims.

i It is a general object of my invention to provide a new and improvedcircuit breaker of the above type which is trip-free in its automaticoperation {and which is durable, dependable and inexpensive tomanufacture.

It is a further object of my invention to provide a new and improvedreset means for an overcenter current responsive tripping mechanism whenused in conjunction with the circuit breaker {of the foregoingdescription.

My invention is especially useful in manually operable currentresponsively tripped circuit breakers used for the connection of thesmall motors directly across a supply source without a startingresistor. These devices are of small physical dimensions and at thepresent time are used with motors up to 7 /2 horsepower.

For a more complete understanding of my invention and a furtherappreciation of its various objects and advantages reference should nowbe had to the following detailed specification taken in conjunction withthe accompanying drawings, in which Fig. 1 is a front view of athree-phase motor starting switch embodying my invention; Fig. 2 is asectional view taken along the line 22 of Fig. 1 looking in thedirection of the arrows and showing the operating mechanism in its onposition; Fig. 3 is a side elevational view of the operating mechanismwith one of the lateral supporting plates removed to show the mechanismin its automatic trip position; Fig. 4 is a view similar to Fig. 3showing the operating mechanism in its reset position; and Fig, 5 is anexploded perspective view of the switch mechanism with various partsbroken away and showing the mechanism in its manual off position.

Referring now to the drawings, my invention in the form shown comprisesa' circuit breaker mechanism mounted upon a base It! made of anysuitable electric insulating material, such as a suitable moldedinsulating compound, the base In serving as a support both for theswitch contacts and for a switch actuating and releasing mechanism. Thebase l0 along with the mechanism mounted thereon is mounted in anenclosing casing having a cover l2. The base It) has an irregular shapedetermined by convenience in supporting the various parts of the device.

By way of illustration I have shown my invention as applied to a threepole or three circuit motor starter, such as might be used with athreephase motor. As best illustrated in Figs. 1, 2 and 5, each of thethree circuits comprises a pair of fixed contacts l3 and [4 connected bysuitable conductors to terminals I! and |8, respectively, at oppositeends of the base III. In the center circuit (Fig. 2) the contact I3 andterminal H are directly connected by a conductor l5. In each outsidecircuit there is included a series hgaten for the current responsivetripping mechanism, as in my prior Patent 2,230,713. Each contact I4 isconnected to the associated terminal l8 by a conductor l6.

Each pair of fixed contacts l3 and I4 is arranged to be connectedtogether by a movable bridging contact |9. The three bridging contactsl9 are mounted upon a common insulating cross arm which is carried atthe end of a pivoted lever 2|. The pivoted lever, or switch member, 2|is part of a switch actuating mechanism which is mounted between twometallic supporting plates 22 and 23 which extend upwardly inparallel'spaced relation from the base l0 substantially in alignmentwith the center phase of the breaker. The switch member 2| is mounted atone end on a fixed pivot 24 carried by the supporting plates 22 and 23.The pivoted lever 2| is formed of two parallel side rails spaced apartand connected together for rigidity by channel-shaped sections, theunsupported end of the lever being provided with an extension carryingthe movable cross arm 20.

The switch member or lever 2| is arranged to be moved between circuitopening and circuit closing positions by a toggle mechanism whichcomprises a pair of links 25 pivotally mounted at one end upon a fixedpivot 26 carried by the supporting plates 22 and 23, and a pair of links21 pivotally connected in parallel spaced relation to the ends of thelinks 25, as by a pin 28. The links 21 are pivotally connected at theiropposite ends to an intermediate point of the switch lever 2|, as byprojections 29 on the lever 2|. As best shown at Figs. 2, 3 and 4, apair of over-center toggle springs 30 is connected between the outerends of the pin 28 and a pin 3| which is movable manually over-centerwith respect to the fixed pivot pin 26.

The manually movable pin 3| to which one end of each over-center spring30 is connected is carried upon a pivoted actuating plate or lever 32.The lever 32 is centrally positioned between the pivoted links and ispivotally mounted upona fixed pivot 33 carried by the supporting plates22 and 23. To permit movement of the pivoted links 25 withoutinterference by the fixed pivot pin 33, the links 25 are slotted, as at34, and the pin 33 passes through the slots.

In order to move the actuating plate 32 upon its pivot 33 and thus tomove the line of action of the toggle springs over-center with respectto the fixed pivot 25 for manual opening and closing operations of thebreaker contacts, I provide a push button linkage comprising a pair ofrocker arms 35 pivotally mounted in parallel spaced relation upon thefixed pivot pin 25 and connected at opposite ends to a pair ofreciprocable push buttons 35 and 35a. The push buttons 36 and 36a extendthrough suitable apertures in the cover I2 of the metal enclosure H. Themovable end of the actuating plate 32 is coupled to the rocker arms 35for movement by camming action as the rocker arms are oscillated by thepush buttons. For this purpose, the rocker arms 35 are provided at oneend with open sided slots 31 into which extends a transverse pin 35fixed upon one side of the actuating plate 32. The slots 31 aregenerally tangent to a circle having its center at the fixed pivot 25,and camming action between the slots 31 and the pin 33 amplifies theangular movement of the actuating lever 32 with respect to angularmovement of the rocker arms 35. The rocker arms 35 are also slottedcentrally in the direction of their length at 31a in order toaccommodate arcuate movement of the spring pin 3| on the plate 32.

, For automatic tripping operation in response to excessive currentthrough the contacts, I provide a spring biased tripping arm andlatching mechanism substantially the same as shown and described in myPatent 2,230,713, issued February 4, 1941, upon an application filedOctober 25. 1939. This mechanism comprises a substantially L- shapedtrip member 40 pivotally mounted as a bell crank upon the fixed pivot 25and having one end connected to a tension spring 41. The spring 4| isarranged to pull the trip member 40 forcibly against the toggle pin 28,thereby to break the toggle and to move the line of action of the togglesprings 30 over-center with respect to the fixed pivot 25. Normally,however, the pivoted trip member 40 is held in retracted position againsthe force of the spring 4| by a latch lever 4 iforming part of a doublelatch lever mechanisnt such as that described in my foregoing Patenii2,230,713. As described in that patent, the late 1 lever 42 is mountedintermediate its ends upo a fixed pivot 43 so that one end is inlatching relation to one end of the trip member 40. The opposite end ofthe latch lever 42 comprises a portion 42a which extends laterally to aposition near the trip member 40 and engages a second latch lever 44.The latch lever 42 is prevented by the latch lever 44 from moving to aposition to release the trip member 40. The lever 42 is biased to latchreleasing position by a tension spring 45 connected between the lever 44and one end of the lever 42. The latch lever 44 is pivotally mountedupon the fixed pivot 24 and is movable against the force of the spring45 to release the latch lever 42.

For the purpose of moving the lever 44 to release the latching mechanismupon excessive current, each outside circuit of the circuit breaker :isprovided with a thermal responsive trippingi/ j mechanism 45 heated bya. current carrying heater (not shown), the heaters being connected inseries; 7

circuit relation in the outside circuits as in my foregoing patents.Each tripping mechanism 45 comprises a generally L-shaped mountingbracket 41 of channel-shaped cross section having extending therefrom anangle bracket 48. Adjustably mounted upon the bracket 41 there isprovided a U-shaped thermal unit comprisin a rigid L- shaped mountingstrip 49 connected to a fiat bimetallic bar 50. The bimetallic member 50is movable into and out of engagement with an arm 5| extending from theside of an over-center trip lever 52. The trip lever 52 is endowed witha snap action by means of an over-center spring 54 connected between thebracket 48 and the trip lever 52. Each over-center trip lever 52 isprovided with an inwardly projecting arm 53 extending toward the centerof the circuit breaker and into position to engage the latch lever 44.This construction of the thermal responsive tripping mechanism isdescribed in greater detail and claimed in my Patent 2,318,987, issuedMay 11, 1943, upon an application filed June 19, 1942.

The pin 38 carried by the actuating plate 32 is so positioned that, whenthe actuating plate is manually moved toward the switch opening positionto reset the breaker after an automatic tripping operation, the pin 38engages the trip lever 40 and forces it back into latching engagementwith the latch lever 42. In this resetting movement the trip member 40first engages the portion 42a of the latch lever 42 and rotates thelatch lever 42 to its latching position, as described in my foregoingPatent 2,230,713, When the latch lever 42 is so returned to the latchingposition the latch spring 45 is stressed and tends to return the secondlatch lever 44 to its latching position. However, the spring 45 isunable, without further aid, to so return the second latch lever 44 whenover-center trip levers 52 of the type herein described are used,because the over-center springs 54 of the trip levers 52 are necessarilystronger than the latching spring 45. It is therefore necessary toprovide separate means operable upon resetting movement for returningthe over-center trip levers 52 to their initial position so that thelatching spring 45 can return the second latch 44 to its latchingposition.

For the purpose of restoring the over-center trip levers 52 to theirnormal positions by resetting movement after an automatic trippinoperation has occurred, I provide a pair of reset levers 55 mountedexternally of the supporting plates 22 and 23 upon fixed pivots 55.These levers are in position to engage the inwardly extending arms 53 ofthe over-center tripping levers 52, and the movable upper ends of thereset levers 55 are coupled by slidable links 51 to opposite ends of thepin 35 which is carried by the actuating plate 32.

Referring now particularly to Figs. 2, 3, 4 and 5, the manual andautomatic operation of '.-iy new and improved circuit breaker will beclear from the following brief description.

At Fig. 5 the mechanism is shown in the manual open position. Thecontacts may be closed manually by depressing the push button 35,thereby to rotate the rocker arms 35 in a clockwise direction, as viewedin the drawings, about the pivot pin 25.

When the rocker arms are thus rotated the lower edges of the open-endedslots 31 in the rocker arms engage the transverse pin 38 on the plate 32in such a position that the pin is forced to slide inwardly in the slots31 thereby to move the actuating plate 32 by camming action about itsfixed pivot 33 in a clockwise direction, as viewed in the drawings. Theapertures 31a in the-rocker arms 35 simply accommodate the transversepin 3| and allow freedom of movement of the actuating plate 32. Thecammin action between the pin 38 and the slots 31 produces a relativelylarge angular movement of the actuating lever 32 as a result of smallangular movement of the rocker levers 35.

When the plate 32 moves in a clockwise direction, it carries with it theattached pin 3| to the ends of which are attached the toggle springs 30.In this manner the line of action of the toggle springs is movedover-center with respect to the fixed pivot 26, so that the toggle linksare biased to the opposite side of the pivot 26. The toggle links 25therefore move in a counterclockwise direction about the fixed pivot 26and strengthen the toggle links 21, thereby to force the pivoted switchmember 2| downwardly and close the contacts. After this operation iscompleted the breaker mechanism is in the position shown at Fig. 2 ofthe drawing.

It will, of course, be understood that manual opening operation issimply the reverse of the closing operation described above. Referringto Fig. 2, the breaker contacts are opened by depressing the push button36a and thus ro ating the rocker arms 35 about the fixed pivot 26 in acounterclockwise direction. In so moving the upper edges of theopen-ended slots 31 in the rocker arms 35 engage the transverse pin 38in such a position that the pin 38 is forced to slide outwardly alongthe slots 31, thereby to rotate the actuating plate 32 in acounterclockwise direction about its fixed pivot 33. Suchcounterclockwise movement of the actuating plate 32 carries the pin 3!and the toggle springs over-center with respect to the fixed pivot 26,and thus breaks the toggle to the position shown at Fig. 5.

Assuming now that the mechanism is in the manual closed position shownat Fig. 2, an automatic tripping operation upon the occurrence of anexcessive current takes place as follows: Upon the occurrence of apredetermined excessive current the thermal strip 50 is heated anddeformed in such a direction that the trip lever 52 is moved slowly in aclockwise direct-ion, as viewed at Fig. 5. As soon as the trip lever 52is carried over-center the trip lever continues in movement with a snapaction under the influence of its over-center spring 54, thereby tobring the inwardly extending arm 53 of the trip lever into strikingengagement with the second latch lever 44. wise direction, as viewed inthe drawings, against the bias of the latch spring 45 and to a positionto release the latch lever 42. When the latch lever 42 is released bythe latch lever 44 the latch spring 45 rotates the lever 42 in acounterclockwise direction, as viewed in the drawings, thereby torelease the latched end of the trip lever 43.

Upon release of the trip lever 40 the spring 4! forcibly rotates themember 40 in a clockwise direction and brings it into strikingengagement with the toggle pin 23. The toggle pin 28 is thus forced tomove to the left, as viewed at Fig. 3, thus breaking the toggle andmoving the toggle springs over-center with respect to the fixed pivot25. This movement of the toggle springs 30 carries the actuating plate32 to a mid-position, as illustrated at Fig. 3. In moving to suchmid-position the plate 32 by camming action moves the rocker levers 35to a mid-position, so that in the trip position of the breaker mecha-The latch lever 44 is thus moved in a clock- 5 i nism the push buttons36 and 35a are also in a mid-position. This positioning of the pushbuttons serves as an indication of the tripped condition of themechanism.

In order to reset the breaker mechanism after an automatic trippingoperation such as that described above, the rocker arms 35 must be movedin a counterclockwise direction beyond their manual open position bydepression of the push button 36a. The reset" position of the mechanismis shown at Fig. 4; and by comparison with Fig. 5 it may be seen that inresetting operation the camming pin 33 on the actuating plate 32 ismoved by the rocker arms 35 to an extreme outward position in the slots31; that is, the actuating plate 32 is rotated to an extremecounterclockwise position. In moving to this position the pin 38 on theplate 32 presses against the upper arm of the pivoted trip member 40 androtates the trip member in a counterclockwise direction against the biasof the spring 4| and beyond its normal latched position. As clearlyshown at Fig. 4 extreme counterclockwise or resetting movement of thetrip member 40 causes the normally latched end of the trip member toengage the lower arm 42a of the latch lever 42, thereby to rotate thelatch lever 42 in a clockwise direction to its latching position. Inmoving to this position the latch lever 42 stresses the latch spring 45and thus biases the second latch lever 44 to its latched position shownat Fig. 5. As pointed out previously, however, the second latch lever 44cannot move to this position until the trip levers 52 on the overcurrenttripping mechanisms 46 are first reset by operation of the reset levers55.

During the resetting movement of the breaker mechanism the reset leversare rotated in a counterclockwise direction by the pin 38 on the plate32. As the pin 38 is moved to its extreme counterclockwise or resetposition it carries with it the reset levers 55, slight sliding movementof the pin 33 with respect to the levers 55 being allowed by theslidable links 51. Thus, during the resetting movement the reset levers55 rotate counterclockwise and engage the tripping arms 53, thereby toforce the tripping levers 52 overcenter to their normal positions asshown at Figs. 1, 2 and 5. With the tripping levers 52 thus removed fromthe path of the latch lever 44 by operation of the reset levers 55, thelatch lever 44 resets itself under the influence of the latching spring45 so that the mechanism assumes the position shown at Fig. 4. When thepush button 35a is released, the tension spring 4| returns the tripmember 40 to its normal latched position shown at Fig. 2 by a slightclockwise movement.

Such clockwise return movement of the trip lever 40 causes a slightclockwise return movement of the actuating plate 32 to the manual open"position shown in Fig. 5, and by camming movement of the pin 38 againstthe slots 31 the rocker arms 35 are moved slightly clockwise to themanual open position. All parts are now fully reset to the open"position shown at Fig. 5 and repared for manual operation to close thebreaker.

While I have described but a single preferred embodiment of my inventionby way of illustration, many modifications will occur to those skilledin the art. For example, while I have illustrated my invention asapplied to the three circuit motor starting switch provided with twoover-current tripping mechanisms for three phase protection, it will beunderstood that my actuating and latching mechanism may be used tooperate any desired number of switch contacts and mtFy be-combined withany desired number of independent over-current tripping mechanisms. Itherefore wish to have it understood that I intend in the appendedclaims to cover ail such modifications as fall within the true spiritand scope of my invention.

What I claim as new and desire to secure by ers Patent of the UnitedStates is:

1. A circuit breaker comprising a switch member movable between open andclosed circuit positions, manually operable means for moving said switchmember including a pivoted actuating member, a trip member biased tomove said switch member to its open circuit position, latch means forsecuring said trip member against its bias including a latch leverbiased to latching position, an over-center trip lever rnovablelnresponse to excessive current thig gh saicLnire. cuit breaker forreleasing said l a tch lever, a nd means for resetting said circuitbreakerlncluding means operable by said actuating membfei'ifiarresetting said over-center trip "lever was normal position.

2. A circuit breaker comprising a switch member movable between open andclosed circuit positions, manually operable means for moving said switchmember including a pivoted actuating member, a trip member biased tomove said switch member to its open circuit position, latch meansincluding a latch lever biased to latching position, an overcenter triplever for releasing said latch lever, means operable by said manuallyoperable means for moving said actuating lever to reset said tripmember, and means operable by said actuating member in said resettingmovement to restore said over-center trip lever to its normal position.

3. A circuit breaker comprising a pair of cooperating switch contacts, aswitch member for moving one of said contacts, manually operable meansincluding a pivoted actuating member for moving said switch memberbetween open and closed circuit positions, a trip member biased to movesaid switch member to its open circuit position, a first latch leversecuring said trip member and provided with a portion adjacent said tripmember, a second latch lever securing said first latch lever, a latchspring connected between said latch levers to bias said first latchlever to release said trip member and to bias said second latch lever tosecure said first latch lever, an over-center trip lever movable inresponse to excessive current through said contacts for moving saidsecond latch lever to release said first latch lever, said over-centertrip lever having an actuating spring arranged to overpower said latchspring, means operated by said manually operable means for moving saidactuating member to reset said trip member, said trip member engagingsaid portion of said first latch lever to return said first latch leverto its latching position, and means actuated by said actuat ing memberin resetting movement for restoring said over-center trip lever tonormal position, thereby to permit said latch spring to reset saidsecond latch lever to secure said first latch lever.

4'. A circuit breaker comprising cooperating switch contacts, a switchmember for moving one of said contacts, manually operable meansincluding a pivoted actuating member for moving said switch memberbetween open and closed circuit positions, a trip memberbiasedetmmovesaid switch member to its. been circuitpositipn. a first latch leversecuring said trip member and p ov ded W th a portion adjacent saidtripmemher, a second latch lever securing. to said first latch lever, alatch miuamonnectedbetween. said latch levers to bias said first latchfiYEnIO release said trip member and to bias said second latch lever tosecure said first latch lever, an over-center trip lever movable inresponse to excessive current through said contacts for moving saidsecond latch lever to release said first latch lever, said over-centertrip lever having an actuating spring arranged to overpower said latchspring, means operated by said manually operable means for moving saidactuating member into engagement with said trip member to reset saidtrip member to its normal latched position, said trip member in movingto said latch position engaging said portion of said first latch leverto return said first latch lever to its latching position, and a pivotedreset lever c o n nected to said actuating member and movable uponresetting movement of said actuating member to restore said over-centertrip lever to its normal position, thereby to permit said latch springto reset said second latch lever to secure said first latch lever.

WILLIAM LAWRENCE BUTLER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,230,713 Butler Feb. 4, 19412,306,244 Butler Dec. 22, 1942 2,318,987 Butler May 11, 1943

